Patent GB-568501-A (GB)
Title: Improvements in or relating to control surfaces of aircraft, ships and torpedoes
IPC: B63H25/38
Filed: 1942-12-18
Abstract: 568,501. Controlling aircraft. WESTLAND AIRCRAFT, Ltd., and GDALIAHU, M. Dec. 18, 1942, No. 18024. [Classes 4 and 114] [Also in Group XXI] An aircraft control surface, such as an aileron, rudder, elevator or tab, or a ship's rudder, or the hydrovanes of a torpedo, has means for varying the angle between the two surfaces at the trailing edge in order to adjust the aerodynamic balance of the control surface. The adjustment may be effected on the ground, and in some cases adjustment consequent upon movement of the control surface may be effected to preserve the balance at the varying angles of deflection during use. Fig. 1 shows a control surface in which the trailing edge comprises two substantially flat plates a hinged at their rear edge d which is connected to a number of control rods c adapted to be secured in a variety of positions. The forward edges of the plates slide in pockets at the rear of the control surface b. Alternatively, the rods c may be connected to fixed points to the rear of the pivot axis of the control member so that the latter is deflected in either direction the trailing edge section is drawn forward. In a modification, two such hinged plates are slotted to clear securing bolts by which the plates a can be clamped to the rear of the control surface in any adjusted position. In other forms, detachable parts of metal, wood or other material forming wedges of various angles are secured to the trailing edge and the most appropriate one selected after trial flights, or the angle of a wooden trailing edge may be varied by planing. In another form, Fig. 9, the angle at the trailing edge may be varied by using packing strips r of various thicknesses. Fig. 3 shows another form in which separate plates a are carried by members e pivoted to brackets on the control member b at f, the forward ends of the members e being urged apart by springs. The two plates are individually adjusted by screws g. Fig. 12 shows similar plates 2, 3 mounted on levers 4, 5 connected by links 8, 9 to two arms of a threearmed lever 10, the third arm of which is connected to a pilot's control so that the two plates can be moved in unison. The lever 10 is mounted on a pivot 11 carried by a member 12 supported on parallel links 13, 14 from. pivots on the control surface b which is pivoted about an axis 20, crossing the member 12 intermediately of its ends, and is movable by the usual controls. The member 12 is connected by a link 17 to a point 18 so that as the control surface b is deflected the plates 2, 3 are brought closer together. Screw adjustments may be provided in the rods 8, 9 and 17 for initial settings. The width of the strip to be varied may be 1.5 to 30 per cent of the chord of the control surface. As applied. to a ship's rudder, the rear edge is champered for a distance of about 5 per cent of the average distance from the pintle to the rear edge, the angle being determined after trial. The hydrovane of a torpedo also may have its trailing edge angle varied to give the desired degree of lightness of control.